People look at the Turrialba volcano as it spewes ashes on May 20, 2016, in Cartago, Costa Rica. The Turrialba volcano started erupting columns of smoke and ash that the wind extended towards the Costa Rican capital, in what according to experts is the strongest eruption in the past six years. (Photo by Ezequiel Becerra/AFP Photo)

Female members of the Chinese People's Liberation Army (PLA) honour guard stand behind a string to ensure that they are in a straight line before a welcoming ceremony for Russian President Vladimir Putin outside the Great Hall of the People in Beijing, China, June 25, 2016. (Photo by Kim Kyung-Hoon/Reuters)

Girls sit inside an empty classroom as they pose for a photograph during a celebration marking the end of the school year in the town of Douma, eastern Ghouta in Damascus, Syria May 21, 2016. (Photo by Bassam Khabieh/Reuters)

Russian President Vladimir Putin (C) and Defence Minister Sergei Shoigu (back) attend a reception to honour graduates of military academies at the Kremlin in Moscow, Russia, June 28, 2016. (Photo by Alexei Druzhinin/Reuters/Sputnik/Kremlin)

A homeless girl asks for alms outside a coffee shop in Mumbai, India, June 24, 2016. (Photo by Danish Siddiqui/Reuters)

Stay Puft Marshmallow Man is seen on the concourse at Waterloo Station, July 11, 2016, in London. Ghostbusters take over Waterloo Station as Stay Puft Marshmallow Man smashes through the concourse during the morning rush-hour. (Photo by Gareth Cattermole/Getty Images)

A man lies in the sea grass at a beach on July 18, 2016 in Qingdao, Shandong Province of China. The enteromorpha prolifera spread on the beaches in Qingdao and were under clearing. (Photo by VCG/VCG via Getty Images)

A fan waves a Brazilian flag before the arrival of the Olympic torch ahead of the Rio 2016 Olympic Games on August 2, 2016 in Sao Goncalo, Rio de Janeiro state, Brazil. The torch will arrive in the city of Rio tomorrow and the Games commence on August 5. (Photo by Mario Tama/Getty Images)